scholarly journals Molecular mechanisms and topological consequences of drastic chromosomal rearrangements of muntjac deer

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuan Yin ◽  
Huizhong Fan ◽  
Botong Zhou ◽  
Yibo Hu ◽  
Guangyi Fan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Chromosome Evolution ◽  
Chromosomal Rearrangements ◽  
Complex Structure ◽  
Early Evolution ◽  
Chromosome Fusion ◽  
Tandem Fusion ◽  
Y Chromosomes ◽  
Topologically Associated Domains ◽  
Male Specific

AbstractMuntjac deer have experienced drastic karyotype changes during their speciation, making it an ideal model for studying mechanisms and functional consequences of mammalian chromosome evolution. Here we generated chromosome-level genomes for Hydropotes inermis (2n = 70), Muntiacus reevesi (2n = 46), female and male M. crinifrons (2n = 8/9) and a contig-level genome for M. gongshanensis (2n = 8/9). These high-quality genomes combined with Hi-C data allowed us to reveal the evolution of 3D chromatin architectures during mammalian chromosome evolution. We find that the chromosome fusion events of muntjac species did not alter the A/B compartment structure and topologically associated domains near the fusion sites, but new chromatin interactions were gradually established across the fusion sites. The recently borne neo-Y chromosome of M. crinifrons, which underwent male-specific inversions, has dramatically restructured chromatin compartments, recapitulating the early evolution of canonical mammalian Y chromosomes. We also reveal that a complex structure containing unique centromeric satellite, truncated telomeric and palindrome repeats might have mediated muntjacs’ recurrent chromosome fusions. These results provide insights into the recurrent chromosome tandem fusion in muntjacs, early evolution of mammalian sex chromosomes, and reveal how chromosome rearrangements can reshape the 3D chromatin regulatory conformations during species evolution.

scholarly journals Heterozygosity and Chain Multivalents during Meiosis Illustrate Ongoing Evolution as a Result of Multiple Holokinetic Chromosome Fusions in the Genus Melinaea (Lepidoptera, Nymphalidae)

2017 ◽  
Vol 153 (4) ◽  
pp. 213-222 ◽  
Author(s):  
Melanie McClure ◽  
Bernard Dutrillaux ◽  
Anne-Marie Dutrillaux ◽  
Vladimir Lukhtanov ◽  
Marianne Elias
Keyword(s):  
Chromosome Evolution ◽  
Taxonomic Revision ◽  
Variable Number ◽  
Chromosome Fusion ◽  
Meiotic Chromosomes ◽  
In Captivity ◽  
Chromosome Fusions ◽  
The Common ◽  
Multiple Spindle ◽  
Complex Chromosome

Mitotic and meiotic chromosomes from 2 taxa of the genus Melinaea, M. satevis cydon and M. “satevis” tarapotensis (Lepidoptera: Nymphalidae), and from hybrids produced in captivity were obtained using an improved spreading technique and were subsequently analyzed. In one of the taxa, the presence of trivalents and tetravalents at diakinesis/metaphase I is indicative of heterozygosity for multiple chromosome fusions or fissions, which might explain the highly variable number of chromosomes previously reported in this genus. Two large and complex multivalents were observed in the meiotic cells of the hybrid males (32 chromosomes) obtained from a cross between M. “s.” tarapotensis (28 chromosomes) and M. s. cydon (40-43 chromosomes). The contribution of the 2 different haploid karyotypes to these complex figures during meiosis is discussed, and a taxonomic revision is proposed. We conclude that chromosome evolution is active and ongoing, that the karyotype of the common ancestor consisted of at least 48 chromosomes, and that evolution by chromosome fusion rather than fission is responsible for this pattern. Complex chromosome evolution in this genus may drive reproductive isolation and speciation, and highlights the difficulties inherent to the systematics of this group. We also show that Melinaea chromosomes, classically considered as holocentric, are attached to unique, rather than multiple, spindle fibers.

Benzene metabolite hydroquinone promotes DNA homologous recombination repair via the NF-κB pathway

2019 ◽  
Vol 40 (8) ◽  
pp. 1021-1030 ◽  
Author(s):  
Xuejing Yang ◽  
Yedan Lu ◽  
Fuhong He ◽  
Fenxia Hou ◽  
Caihong Xing ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Molecular Mechanisms ◽  
Chromosomal Rearrangements ◽  
Critical Role ◽  
Environmental Pollutants ◽  
Environmental Pollutant ◽  
Osteosarcoma Cell ◽  
Dna Double Strand Breaks ◽  
Hematopoietic Stem

Abstract Benzene, a widespread environmental pollutant, induces DNA double-strand breaks (DSBs) and DNA repair, which may further lead to oncogenic mutations, chromosomal rearrangements and leukemogenesis. However, the molecular mechanisms underlying benzene-induced DNA repair and carcinogenesis remain unclear. The human osteosarcoma cell line (U2OS/DR-GFP), which carries a GFP-based homologous recombination (HR) repair reporter, was treated with hydroquinone, one of the major benzene metabolites, to identify the potential effects of benzene on DSB HR repair. RNA-sequencing was further employed to identify the potential key pathway that contributed to benzene-initiated HR repair. We found that treatment with hydroquinone induced a significant increase in HR. NF-κB pathway, which plays a critical role in carcinogenesis in multiple tumors, was significantly activated in cells recovered from hydroquinone treatment. Furthermore, the upregulation of NF-κB by hydroquinone was also found in human hematopoietic stem and progenitor cells. Notably, the inhibition of NF-κB activity by small molecule inhibitors (QNZ and JSH-23) significantly reduced the frequency of hydroquinone-initiated HR (−1.36- and −1.77-fold, respectively, P < 0.01). Our results demonstrate an important role of NF-κB activity in promoting HR repair induced by hydroquinone. This finding sheds light on the underlying mechanisms involved in benzene-induced genomic instability and leukemogenesis and may contribute to the larger exploration of the influence of other environmental pollutants on carcinogenesis.

CHROMOSOME BANDING HOMOLOGIES OF A TANDEM FUSION IN RIVER, SWAMP, AND CROSSBRED BUFFALOES (BUBALUS BUBALIS)

1982 ◽  
Vol 24 (6) ◽  
pp. 667-673 ◽  
Author(s):  
T. A. Bongso ◽  
M. Hilmi
Keyword(s):  
First Generation ◽  
Bubalus Bubalis ◽  
Chromosome 9 ◽  
Chromosome 4 ◽  
Centromere Region ◽  
Hybrid Female ◽  
Banding Patterns ◽  
C Banding ◽  
Tandem Fusion ◽  
Y Chromosomes

The chromosomes of the Murrah (River), Swamp (Malaysian kerbau), F1 hybrid (Murrah × Swamp) and first generation backcross (F1 hybrid female × Murrah male) buffaloes (Bubalus bubalis L.) were studied using Giemsa (G) and centromeric (C) banding techniques. The diploid chromosome number for the Murrah was 2n = 50, Swamp 2n = 48, F1 hybrid 2n = 49 and two backcross animals had 2n = 49 and 2n = 50, respectively. The largest two metacentric chromosomes of the Swamp resulted from a tandem fusion between the two chromosomes 4p and 9, respectively, of the Murrah karyotype. The F1 hybrid (2n = 49) and one of the backcrosses (2n = 49) had karyotypes intermediate to the Murrah and Swamp parents. The C banding patterns were useful in identifying the X and Y chromosomes of the buffalo and demonstrated that a major portion of the centromere region of chromosome 9 was not incorporated into chromosome 4 during the tandem fusion.

scholarly journals Direct glia-to-neuron transdifferentiation gives rise to a pair of male-specific neurons that ensure nimble male mating

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Laura Molina-García ◽  
Carla Lloret-Fernández ◽  
Steven J Cook ◽  
Byunghyuk Kim ◽  
Rachel C Bonnington ◽  
...  
Keyword(s):  
Cell Fate ◽  
Molecular Mechanisms ◽  
Male Mating ◽  
Sexually Dimorphic ◽  
Innate Behaviour ◽  
One Step ◽  
Males And Females ◽  
Direct Transdifferentiation ◽  
Male Specific ◽  
Mating Sequence

Sexually dimorphic behaviours require underlying differences in the nervous system between males and females. The extent to which nervous systems are sexually dimorphic and the cellular and molecular mechanisms that regulate these differences are only beginning to be understood. We reveal here a novel mechanism by which male-specific neurons are generated in Caenorhabditis elegans through the direct transdifferentiation of sex-shared glial cells. This glia-to-neuron cell fate switch occurs during male sexual maturation under the cell-autonomous control of the sex-determination pathway. We show that the neurons generated are cholinergic, peptidergic, and ciliated putative proprioceptors which integrate into male-specific circuits for copulation. These neurons ensure coordinated backward movement along the mate’s body during mating. One step of the mating sequence regulated by these neurons is an alternative readjustment movement performed when intromission becomes difficult to achieve. Our findings reveal programmed transdifferentiation as a developmental mechanism underlying flexibility in innate behaviour.

scholarly journals In situ dissection of domain boundaries affect genome topology and gene transcription in Drosophila

2019 ◽  
Author(s):  
Rodrigo G. Arzate-Mejía ◽  
Angel Josué Cerecedo-Castillo ◽  
Georgina Guerrero ◽  
Mayra Furlan-Magaril ◽  
Félix Recillas-Targa
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Topological Defects ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Domain Boundaries ◽  
Topologically Associated Domains ◽  
Genetic Sequences

AbstractThe molecular mechanisms responsible for Topologically Associated Domains (TADs) formation are not yet fully understood. In Drosophila, it has been proposed that transcription is fundamental for TAD organization while the participation of genetic sequences bound by Architectural Proteins (APs) remains controversial. Here, we investigate the contribution of domain boundaries to TAD organization and the regulation of gene expression at the Notch gene locus in Drosophila. We find that deletion of domain boundaries results in TAD fusion and long-range topological defects that are accompanied by loss of APs and RNA Pol II chromatin binding as well as defects in transcription. Together, our results provide compelling evidence on the contribution of discrete genetic sequences bound by APs and RNA Pol II in the partition of the genome into TADs and in the regulation of gene expression in Drosophila.

scholarly journals Timing mechanism of sexually dimorphic nervous system differentiation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Laura Pereira ◽  
Florian Aeschimann ◽  
Chen Wang ◽  
Hannah Lawson ◽  
Esther Serrano-Saiz ◽  
...  
Keyword(s):  
Nervous System ◽  
Transcription Factors ◽  
Molecular Mechanisms ◽  
Sex Chromosome ◽  
Sexually Dimorphic ◽  
Neuron Type ◽  
Chromosome Configuration ◽  
Opposite Sex ◽  
Male Specific ◽  
Spatial Specificity

The molecular mechanisms that control the timing of sexual differentiation in the brain are poorly understood. We found that the timing of sexually dimorphic differentiation of postmitotic, sex-shared neurons in the nervous system of the Caenorhabditis elegans male is controlled by the temporally regulated miRNA let-7 and its target lin-41, a translational regulator. lin-41 acts through lin-29a, an isoform of a conserved Zn finger transcription factor, expressed in a subset of sex-shared neurons only in the male. Ectopic lin-29a is sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron-type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional sex- and neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner.

scholarly journals Male-specific CREB signaling in the hippocampus controls spatial memory deficits in a mouse model of autism and intellectual disability

2018 ◽  
Author(s):  
Marta Zamarbide ◽  
Adele Mossa ◽  
Molly K. Wilkinson ◽  
Heather L. Pond ◽  
Adam W. Oaks ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Mouse Model ◽  
Neurodevelopmental Disorders ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Coiled Coil ◽  
Autism Spectrum ◽  
Behavioral Studies ◽  
Males And Females ◽  
Male Specific

ABSTRACTBackgroundThe prevalence of neurodevelopmental disorders is biased towards males with male: female ratios of 2:1 in intellectual disability (ID) and 4:1 in autism spectrum disorder (ASD). However, the molecular mechanisms of such bias remain unknown. While characterizing a mouse model for loss of the signaling scaffold coiled-coil and C2 domain containing 1A (CC2D1A), which is mutated in ID and ASD, we identified biochemical and behavioral differences between males and females, and explored whether CC2D1A controls male-specific intracellular signaling.MethodsCC2D1A is known to regulate phosphodiesterase 4D (PDE4D). We tested for activation PDE4D and downstream signaling molecules such as CREB in the hippocampus of Cc2d1a-deficient mice. We then performed behavioral studies in females to analyze learning and memory, social interactions, anxiety and hyperactivity. Finally, we targeted PDE4D activation with a PDE4D inhibitor to define how changes in PDE4D and CREB activity affect behavior in males and females.ResultsWe found that in Cc2d1a-deficient males PDE4D is hyperactive leading to a reduction in CREB signaling, but this molecular deficit is not present in females. Cc2d1a-deficient females only show impairment in novel object recognition, and no other cognitive and social deficits that have been found in males. Restoring PDE4D activity using an inhibitor rescues male-specific cognitive deficits, but has no effect on females.ConclusionsOur findings show that CC2D1A regulates intracellular signaling in a male-specific manner in the hippocampus leading to male-specific behavioral deficits. We propose that male-specific signaling mechanisms are involved in establishing sex bias in neurodevelopmental disorders.

scholarly journals Gene-level, but not chromosome-wide, divergence between a very young house fly proto-Y chromosome and its homologous proto-X chromosome

2020 ◽  
Author(s):  
Jae Hak Son ◽  
Richard P. Meisel
Keyword(s):  
Gene Expression ◽  
Y Chromosome ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
House Fly ◽  
Evolutionary Divergence ◽  
Y Chromosomes ◽  
Mitochondrial Functions ◽  
Xx Males ◽  
Y Chromosome Evolution

AbstractX and Y chromosomes are usually derived from a pair of homologous autosomes, which then diverge from each other over time. Although Y-specific features have been characterized in sex chromosomes of various ages, the earliest stages of Y chromosome evolution remain elusive. In particular, we do not know whether early stages of Y chromosome evolution consist of changes to individual genes or happen via chromosome-scale divergence from the X. To address this question, we quantified divergence between young proto-X and proto-Y chromosomes in the house fly, Musca domestica. We compared proto-sex chromosome sequence and gene expression between genotypic (XY) and sex-reversed (XX) males. We find evidence for sequence divergence between genes on the proto-X and proto-Y, including five genes with mitochondrial functions. There is also an excess of genes with divergent expression between the proto-X and proto-Y, but the number of genes is small. This suggests that individual proto-Y genes, but not the entire proto-Y chromosome, have diverged from the proto-X. We identified one gene, encoding an axonemal dynein assembly factor (which functions in sperm motility), that has higher expression in XY males than XX males because of a disproportionate contribution of the proto-Y allele to gene expression. The up-regulation of the proto-Y allele may be favored in males because of this gene’s function in spermatogenesis. The evolutionary divergence between proto-X and proto-Y copies of this gene, as well as the mitochondrial genes, is consistent with selection in males affecting the evolution of individual genes during early Y chromosome evolution.

scholarly journals Pseudoautosomal gene SHOX exhibits sex-biased random monoallelic expression and contributes to sex difference in height

2021 ◽  
Author(s):  
Atsushi Hattori ◽  
Atsuhito Seki ◽  
Naoto Inaba ◽  
Kazuhiko Nakabayashi ◽  
Kazue Takeda ◽  
...  
Keyword(s):  
Sex Difference ◽  
Sex Chromosome ◽  
Phenotypic Diversity ◽  
Pseudoautosomal Region ◽  
Monoallelic Expression ◽  
Adult Women ◽  
Adult Men ◽  
Y Chromosomes ◽  
Male Specific ◽  
Novel Model

AbstractAdult men are, on average, ∼13 cm taller than adult women. Although previous studies have suggested a significant contribution of sex chromosomal genes to sexual dimorphism in height, all attempts to identify a male-specific growth gene have failed. In the present study, we analyzed transcripts from cartilage tissues, and found that the expression of SHOX, a growth-promoting gene in the pseudoautosomal region on the X and Y chromosomes, was lower in females than in males. DNA methylation analyses showed that SHOX has some characteristics of genes subjected to X chromosome inactivation (XCI). These findings indicate that sex difference in human height is mainly ascribed to incomplete spreading of XCI on a pseudoautosomal gene. More importantly, RT-PCR of fibroblast clones revealed XCI-independent random clonal monoallelic expression of SHOX. We presume that during eutherian evolution, SHOX translocated from an autosome to the proto-sex chromosome without losing the epigenetic memory of random clonal monoallelic expression and subsequently underwent partial XCI. This study provides a novel model of epigenetic gene regulation leading to phenotypic diversity in humans.

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